ch 11 human phys Flashcards | Quizlet

What are the two major functional groups of the efferent PNS?

Somatic motor neurons and autonomic neurons.

What do somatic motor neurons control?

Skeletal muscles, mostly voluntarily.

What do autonomic neurons control?

Smooth and cardiac muscle, many glands, lymphoid tissue, and some adipose tissue.

Is autonomic control mostly voluntary or involuntary?

Mostly involuntary.

What does the sympathetic branch promote?

Arousal, activity, and "fight-or-flight."

What does the parasympathetic branch promote?

Homeostasis, maintenance, and "rest-and-digest."

What is autonomic antagonistic control?

Two nervous inputs control an organ with opposite effects.

How does the sympathetic system affect heart rate?

It increases heart rate.

How does the parasympathetic system affect heart rate?

It slows heart rate.

What are three ways the body coordinates homeostatic responses?

Autonomic, endocrine, and behavioral responses.

What does the hypothalamus regulate?

Water balance, temperature, and hunger.

What does the pons help regulate?

Respiration.

What does the medulla regulate?

Respiration, cardiac function, vomiting, and swallowing.

What tissues can autonomic pathways target?

Smooth muscle, cardiac muscle, glands, lymphoid tissue, and adipose tissue.

Are autonomic effects always consciously controlled?

No. Their control is unconscious.

What is the vagus nerve?

A major parasympathetic nerve carrying about 75% of parasympathetic fibers.

What does the vagus nerve carry?

Sensory information from organs and output from the brain to organs.

What does "bi-synaptic" mean in the autonomic system?

The pathway contains two synapses and two neurons.

What are ganglia?

Collections of neurons outside the CNS.

What neurotransmitter do both autonomic divisions use at ganglia?

Acetylcholine (ACh).

What neurotransmitter does the parasympathetic system use at target tissues?

Acetylcholine (ACh).

What neurotransmitter does the sympathetic system usually use at target tissues?

Norepinephrine (NE).

What are varicosities?

Swellings on autonomic axons that release neurotransmitters.

What is a neuroeffector junction?

The area where autonomic neurons release neurotransmitters onto target tissues.

What does the adrenal medulla release?

Epinephrine (adrenaline) into the bloodstream.

What activates the adrenal medulla?

Spinal sympathetic input.

What is the adrenal medulla considered?

A modified sympathetic ganglion.

How does epinephrine from the adrenal gland spread through the body?

It is released into the bloodstream.

What does sympathetic activity do to the pupils?

Dilates them.

What does sympathetic activity do to heart rate and stroke volume?

Increases them.

What does sympathetic activity do to some blood vessels and bronchioles?

Causes dilation.

What does sympathetic activity do to fat?

Promotes fat breakdown.

What does sympathetic activity do to digestion?

Inhibits digestion.

What does sympathetic activity do to urination?

Inhibits urination.

What neurotransmitter does the parasympathetic system use at target tissues?

Acetylcholine (ACh).

What receptors does parasympathetic ACh activate?

Muscarinic receptors.

What type of receptors are muscarinic receptors?

Metabotropic, G protein-coupled receptors.

What does parasympathetic activity do to the pupils?

Constricts them.

What does parasympathetic activity do to the bronchioles?

Constricts them.

What does parasympathetic activity do to heart rate?

Slows it.

What does parasympathetic activity do to digestion?

Stimulates digestion.

What does parasympathetic activity do to insulin release?

Stimulates insulin release.

What does parasympathetic activity do to urination

Stimulates urination.

What is the somatic motor pathway responsible for?

Voluntary control of skeletal muscles.

Can skeletal muscle activation be involuntary?

Yes, through spinal reflex pathways.

Are motor neuron axons mostly myelinated?

Yes.

How many neurons are in a somatic motor efferent pathway?

One neuron.

How many neurons are in an autonomic efferent pathway?

Two neurons.

What neurotransmitter is used at the somatic motor neuron-target synapse?

Acetylcholine.

What type of receptor does ACh activate at skeletal muscle?

Nicotinic ACh receptors.

What type of effect does somatic motor ACh have on skeletal muscle?

Excitatory; it causes muscle contraction.

What are neurons that innervate muscle fibers called?

Motor neurons.

What are the synapses between motor neurons and muscle fibers called?

Neuromuscular junctions (NMJs).

Why are NMJs large, branched, and powerful?

To reliably activate their target muscle.

What neurotransmitter is released at an NMJ?

Acetylcholine (ACh).

What triggers ACh release at the NMJ?

Ca²⁺ entering the motor neuron terminal.

What receptors does ACh bind to at the NMJ?

Nicotinic ACh receptors.

What ion enters the muscle fiber after ACh receptor activation?

Na⁺.

What happens when the muscle fiber depolarizes?

The muscle fiber contracts.

What is the basic sequence of an NMJ?

AP → Ca²⁺ influx → ACh release → Na⁺ influx → depolarization → contraction.